Conventionally, the structure shown in FIG. 8 is well-known as this kind of fuel supply device. With this fuel supply device, fuel F which is stored in a fuel tank 1 is introduced to a fuel pump 3 through a fuel filter 2 by which the fuel F is filtered. The fuel F is atomized and injected to an intake pipe or a combustion chamber of an internal combustion engine by a fuel injection nozzle 4 while the fuel F is pressurized to or over a specific pressure by the fuel pump 3 and supplied to the fuel injection nozzle 4.
In this figure, the numerical 5 is a pressure regulator which is disposed between the fuel pump 3 and the fuel injection nozzle 4, and regulates the pressure of the fuel F that is supplied to the fuel injection nozzle to a specific pressure. The pressure of the fuel F is regulated by returning excess fuel F to the fuel tank 1 through a return pipe 6.
Furthermore, the inside of the fuel filter 2 is divided by a filter member (a filter paper etc.) 7 into two rooms which are the upstream side and the downstream side, namely, upstream room 8 and downstream room 9.
Here, with this sort of conventional fuel supply device, following problems remain to be solve.
With the aforementioned conventional fuel supply device, the upstream room 8 of the fuel filter 2 is connected to the inside of the fuel tank 1 which is located above and is filled up with the fuel F, so as to receive pressure head equivalent to the fuel level height of the fuel F in the fuel tank 1.
Meanwhile, the fuel F in the downstream room 9 is sucked by the fuel pump 3 to result the pressure of the downstream room 9 to be lower than that of the upstream room 8.
Vapor is generated in the fuel F due to the depression at the time when the fuel F is moved by the pressure balance from the upstream room 8 to the downstream room 9, or due to heating of the fuel F in the fuel supply passage by the environmental temperature increase.
In this manner, when vapor is generated in the fuel F, all the vapor is sucked to the fuel pump 3. When the amount of the vapor excesses the discharging capacity of the fuel pump 3, the fuel discharging amount of the fuel pump 3 is insufficient.
The present invention is devised in the light of such conventional problems. The purpose of the present invention is to provide a fuel supply device and a fuel filter that is utilized to the fuel supply device, which can ensure the fuel discharging amount of the fuel pump by satisfactory removing of vapor which is generated in the fuel sucked by the fuel pump.